High Idle Speed
- Check switch condition signal circuit. See CODE 51 in TESTS W/CODES - EXCEPT OBD-II article in the ENGINE PERFORMANCE section.
- Check Idle Air Control (IAC) valve circuit.
- Check A/C signal circuit.
- Check ECM power source circuit (ignition keyed).
- Check clutch start switch circuit on M/T.
- Check ECM back-up power circuit (battery)